1. Field of the Invention
The present invention relates to a disk reproducing apparatus capable of reproducing image data recorded on a disk-shaped recording medium, such as a digital versatile disk (DVD), and more particularly to a disk reproducing apparatus including an A-B repeat reproduction function.
2. Description of Related Art
In recent years, disk-shaped recording media, such as the DVDs, having large capacities have been rapidly developed, and the image data recorded on the DVDs is reproduced by a disk reproducing apparatus. Moreover, a Moving Picture Coding Expert Group (MPEG) compressing technique is generally used for recoding digital image data onto a DVD.
In the MPEG compressing technique, the processing at the time of coding, reproducing, and editing is performed by a group called as a video object unit (VOBU). Incidentally, one VOBU is sometimes treated as one group of pictures (GOP).
Now, the image data in a VOBU is generally composed of three kinds of pictures of I/P/B pictures, and each frame in the VOBU is distributed to any of the I picture, the P picture, and the B picture to be coded.
Hereupon, the I picture indicates a screen capable of being compressed using only the information in its own screen without using the correlated information of the other screens before and after the screen in time, and the compression similar to the compression of the Joint Photographic Experts Group (JPEG) is performed to the I picture as a still image (intra-frame encoding). Moreover, the P picture indicates a screen expressed by the correlated information from a past screen in time, and is coded by referring to a past I picture or a past P picture (forward prediction). Moreover, the B picture indicates a screen expressed by the correlated information from before and after screens in time, and is coded by referring to an I picture or a P picture (both-direction prediction).
At the time of the reproduction of image data having such a configuration, the I picture is first reconstructed, and then the P picture and the B picture are reconstructed on the basis of the I picture.
On the other hand, if fast-forward reproduction or fast-backward reproduction is performed by a disk reproducing apparatus, a method of only reproducing (displaying) the I pictures is general (the P pictures can be also used for the fast-forward reproduction). That is, in the fast-forward reproduction and the fast-backward reproduction, I pictures before (past) and after (future) predetermined times are sequentially displayed. For example, an I picture before or after a predetermined number of VOBUs by the VOBU (e.g., the first I picture at the VOBU) is displayed.
Furthermore, some disk reproducing apparatus include the A-B repeat reproduction function of setting a repeat starting point (point A) and a repeat ending point (point B) with an input unit of a remote control apparatus or the like during the reproduction of image data, and of repeating reproduction in the A-B section.
For example, Japanese Patent Application Laid-Open Publications No. 2004-241051, No. 2003-235014, No. 2005-071551, and No. 2001-126380 disclose techniques pertaining to the A-B repeat reproduction.
Now, the fast-forward reproduction and the fast-backward reproduction can be executed even during the A-B repeat reproduction, and the I pictures are displayed at predetermined time intervals (e.g. at each time of skipping two VOBUs) also in this case.
FIGS. 5A and 5B are explanatory diagrams showing fast-forward reproduction processing and fast-backward reproduction processing, respectively, at the A-B repeat reproduction, and the FIGS. 5A and 5B show the case where the point A (repeat starting point) is set in VOBU #n−2 reproduction and the point B (repeat ending point) is set in VOBU #n+5 reproduction. Incidentally, although the FIGS. 5A and 5B show the case where the first I picture in each VOBU is reproduced in both of the fast-forward reproduction and the fast-backward reproduction for simplifying the description, there are the cases where the I pictures in the inner parts of the VOBUs are reproduced.
For example, as shown in FIG. 5A, if the fast-forward reproduction (e.g. skipping two VOBUs) is instructed at a point C where the image data in VOBU #n−1 is being reproduced by the A-B repeat reproduction, then the I pictures are reproduced in the order of the first I picture I, in VOBU #n, the first I picture In+2 in VOBU #n+2, . . . . Then, when the first I picture In+6 in VOBU #n+6 is reproduced, it is judged that the fast-forward reproduction has been performed to the point B, and the reproduction returns to the point A to repeat the A-B repeat reproduction. At this time, the judgment of the arrival of the fast-forward reproduction at the point B is performed on the basis of the time information of the point B and the reproduced time information of the I pictures. Consequently, the arrival of the fast-forward reproduction at the point B cannot be judged until the I picture In+6, which has passed the point B, is reproduced. Consequently, during the period of from the time when the judgment of the arrival of the fast-forward reproduction at the point B has been made to the time when the fast-forward reproduction returns to the point A, the I picture In+6, which is an image out of the A-B section, is being displayed.
Moreover, as shown in FIG. 5B, if the fast-backward reproduction (e.g. skipping two VOBUs) is instructed at a point D where the image data in VOBU #n+4 is being reproduced by the A-B repeat reproduction, then the I pictures are reproduced in the order of the first I picture In+4 in the VOBU #n+4, the first I picture In+2 in VOBU #n+2, . . . . Then, when the first I picture In−2 in VOBU#n−2 is reproduced, it is judged that the fast-backward reproduction has been performed to the point A, and the reproduction returns to the point A to repeat the A-B repeat reproduction. Consequently, also in the first-backward reproduction, during the period to the time when the fast-backward reproduction returns to the point A, the I picture In−2, which is an image out of the A-B section, is similarly being displayed.
In this manner, if the image data corresponding to the points A and B set in A-B repeat reproduction is not the first I picture of each VOBU, the images out of the A-B section are displayed during the period of from the time when the fast-forward reproduction or the fast-backward reproduction has passed an end point of the A-B section (point A or point B) to the time when the processing returns to the point A. Consequently, there is the possibility that the display of the images out of the set section may make a user uncomfortable.